Disease of the mouth

Almost always found in new fish who run into the glass a lot. Treat with antibiotics for external infections. May also be from aggression between fish in which case must address underlying issue with fish psychology.

External infections on the body or fins

Fungus looking lesions: Opportunistic bacterial infections from either injury from other fish/environment or from concurrent parasitic infection. Can also occur if water quality is slipping slowly over time. Common in tangs.

Discolored areas can be from:

  • Getting stung by corals : common in clownfish
  • Long term dietary deficiency or lack of diversity can cause color changes.
  • Some older fish get hyper pigmentation for unknown reasons. It could be hormonal imbalances.  Seen in tangs and angelfish on occasion

Fin or tail rotting or cloudy: Usually bacterial and from either poor water quality, high stress, or concurrent parasitic infection. Treat with external bacteria antibiotics but must solve underlying problem to prevent recurrence.

Respiratory (gill) Problems

If all water parameters are in good shape and fish has not recently been exposed to toxins or high ammonia/nitrite, gill parasites such as amyloodinium and cryptocaryon may be present. Parasites favor gill tissue but in most infections you see some signs other than fast breathing ( cloudy fins/eyes, spots on body)

Specific problems with the eyes

Cloudy eyes can be:

  • primarily a bacterial infection from an injury like a scratch, which fish get in transport or from fighting other fish. Treat with antibiotics for external bacteria
  • secondary from a a bacterial infection made possible from a primary parasite such as cryptocaryon or the external flatworm neobenedenia

Puffy or popped out eyes (pop-eye):

  • One sided: Usually from injury. Can have gas behind or above the eye. Treat with antibiotics for external infections for 3 days. If signs do not subside, try erythromycin.
  • Both eyes: Usually a systemic infection. Best shotgun treatment may be erythromycin bath or food but the information is anecdotal and from personal experience
  • Both eyes with gas can also result from a high concentration of nitrogen gas in the water, often caused by a leak in a pipe before a powerful water pump. Air is pulled into the line at pressure and gas is forced into solution. For some reason the gas comes out of solution within some fishes gills, fins, and behind fishes eyes and this varies in degree and location with fish species and water chemistry etc. If you have many fish with gas behind the eyes or in the fins, this situation is highly likely.

Visible Spots on the body

White spots: Almost certainly marine ich (cryptocaryon) however to be certain must look under microscope. Looks different on different fish.

  • Clear pinpoint spots on most angelfish.
  • Slimy patches on pufferfish.
  • Cloudy raised bumps on blue tangs.
  • Very difficult to see on yellow tangs, must look at body at an angle for small raised areas. Easier to see on fins.
  • On lionfish it's cloudy area's on clear parts of fins and cloudy eyes.
  • Wrasses, mandarin gobies, and very healthy reef fish less susceptible but any fish may become infected in a high enough parasite burden.

Black spots:

  • Stings from corals: common on clownfish and some damselfish
  • Black Ich: Black flatworm parasites common on tangs, especially the yellow tang

Little bugs or worms attached if you look closely:

  • Could be parasitic flatworms or crustaceans (isopods/copepods)
  • A strange teardrop rice grain sized inclusion is common seasonally on the fins of tangs (especially yellow tangs) and does not seem to effect them.